The need for control of cursor positions on computer screens and other analogous control functions is well known. Mice, trackballs, and graphics tablets are common solutions to this need. Isometric pointing devices, which have little or no travel, have also been marketed. A popular implementation of an isometric device is the isometric joystick used by IBM (Track-point.TM.) and other computer manufacturers, wherein a miniature isometric joystick is placed on the keyboard in or near the key cluster. For example, many manufacturers will place the joystick between the G, B, and H keys. Another isometric device is the PortaPoint.RTM., marketed by Interlink Electronics, Inc., the applicant for the present invention.
Along with pointing, most Graphic User Interfaces (GUI's) require "clicking" and "dragging" operations, which are usually performed by depressing a switch while manipulating the pointing device. This requires a separate mechanical switch, the manipulation of which, in conjunction with the manipulation of the pointing device, is considered by many to be clumsy. On many portable computers, the thumb must be used to actuate the click buttons, which is particularly detrimental to the dragging operation.
There is a need, therefore, from both a cost and ergonomic viewpoint, for a pointing device having the click function incorporated therein.